Contamination of waste water or groundwater with nitro-containing organic chemical compounds such as aromatic explosives presents a considerable disposal problem. The manufacture of 2,4,6-trinitrotoluene (TNT), for example, can result in the production of extremely toxic waste water containing 50-125 mg/L TNT.
Traditional methods of treatment of this waste water, frequently called pinkwater, have employed activated carbon which has some inherent disadvantages. First, the loading of explosives on carbon can present a safety problem, and second, the loaded carbon cannot be safely regenerated so there is a secondary disposal problem.
A newer method of treating contaminated waste water and groundwater is to utilize advanced oxidation. This involves oxidizing the wastes by employing highly reactive oxidative species such as hydroxyl radicals. There are many methods of generating hydroxyl radicals including photolysis of hydrogen peroxide, photolysis of ozone, ozone with hydrogen peroxide, and ozone at alkaline pH.
Andrews et al. (U.S. Pat. No. 4,038,116) and others have employed ultraviolet (UV) light along with hydrogen peroxide or acetone to treat TNT waste.
While this method is capable of reducing TNT levels to &lt;1 ppm, it does not produce waste water which can pass the type of fish toxicity tests imposed by environmental regulatory requirements.
Layne et al. have described use of UV/ozone to treat TNT and other aromatic explosives ("Ultraviolet-Ozone Treatment of Pink Waste Water, A Pilot Scale Study", Mason & Hanger-Silas Mason Co. Inc., Iowa Army Ammunition Plant, Middleton, Iowa, AD-B 068215, 1982).
Ozone treatment has generally been carried out around pH 7.0 to 9.0, and is very costly where treatment has to provide an effluent capable of passing a fish toxicity test as well as having a discharge level of &lt;1 ppm.